4Th Class Power Engineering Chapter 57

The three T's of combustion?

The amount of air required to supply just enough oxygen for complete combustion is called the _______ _______.

A typical composition of burned flue gases may consist of what five gases?

Fuels can be classified into three groups.

Three types of solid fuels?

What is the most popular grade of liquid fuel for furnaces and boilers?

Grades 4,5 and 6 fuel oils need to be heated to about ____°C in order to be satisfactorily burned.

Two examples of liquefied petroleum gases (LPG) are?

The heating value of a fuel depends on the amount of

1.

2.

3.

Large coal particles are used in a _______ stoker

Three types of mechanical stokers.

When Shutting off an air/steam and oil atomizing burners which should be shut off first? The air/steam or oil.

Too little air will produce a _____, _____ smoke while to much air will produce a _______colored smoke

How often should burners be cleaned?

The amount of excess air can be determined by the _______ of CO2 in the flue gases.

Flue gas analysis is used both for _________ and _________.

The approximate amount of excess air for burning fuel oil is

A. 50%

B. 5%

C. 25%

D. 15%

Two operating factors that may cause a rise in a boilers net stack temperature are?

An internally fired boiler:

1) Must be a watertube type

2) Is less efficient than an externally fired unit

3) Requires a setting

4) Has the furnace surrounded by water

5) Utilizes a high amount of refractory and/or firebrick

Low fuel _____ in oil burners produces unsafe conditions of burning.

1) Viscosity

2) Flow

3) Pressure

4) Volume

5) Temperature

If not enough air is given to an oil fired flame:

1) The flame will have a bluish-purple color

2) A blue-gray smoke will issue from the stack

3) The flame will have a dazzling yellow color

4) The flame will be a dark smoky flame

5) The steam temperature will rise

In a steam atomizing oil burner, the _____ travels through the central portion of the burner.

1) Oil

2) Heat

3) Fire

4) Steam

5) Air

Engineers must understand the importance of combustion in order to:

1. Order the right grade of fuel

2. Burn the fuel completely

3. Produce smokeless fires

4. Minimize the danger of explosion

A) 2, 3

B) 1, 2, 3, 4

C) 2, 3, 4

D) 1, 3

E) 1, 2

The combustion equation S + O2=:

1) SO₂ + heat

2) SO₂ + S

3) 2SO₂ + heat

4) 2S + O

5) SO₂

Too much air for a gas burner will tend to:

1) Cause excessive furnace temperatures

2) Cause the burner to corrode

3) Reduce the radiant heat from the fire

4) Move the flame away from the burner

5) Cause furnace pulsating

To which of the following oil burners is the oil supplied under high pressure?

1) Mechanical atomizing burner

2) Multi-spud burner

3) Steam atomizing burner

4) Rotary cup burner

5) Air atomizing burner

When using mechanical fuel oil atomization:

1) Dry saturated steam or superheated steam should be used

2) High pump pressure is required

3) 35 to 40 kPa oil pressure is required

4) Steam pressure is required to keep the bypass open

5) 70 kPa steam pressure is required at the burner

The approximate amount of excess oxygen for gaseous fuel is:

1) 10%

2) 5%

3) 7%

4) 2%

5) 15%

When removing a steam atomizing oil burner from service, the proper sequence is:

1) Stop the oil, purge oil side, stop the steam, remove burner

2) Stop the steam, purge steam side, stop the oil, remove burner 3) Stop the steam, stop the oil, remove burner

4) Purge oil side, stop the steam, remove burner

5) Stop the oil, stop the steam remove burner

When oil burners are not in use, they should be removed from the furnace, or the heat may cause:

1) Evaporation of the fuel

2) Speed reduction of the rotary cup

3) Seizure of the sprayer plate

4) Corrosion of the burner

5) A buildup of carbon in the burner

Insufficient air for combustion will result in:

1. Carbon in the flue gases

2. High oxygen reading in the flue gases

3. Low oxygen reading in the flue gases

4. High CO in the flue gases

5. Higher than normal flue gas temperature

A) 1, 2, 3

B) 2, 3, 4

C) 1, 3, 4

D) 1, 3, 5

E) 3, 4, 5

When lighting up an oil fired boiler that employs steam atomizing oil burners, the:

1) Draft fans must be at 50% of full capacity

2) Burner must be purged

3) Steam atomizing valve is opened before the fuel valve

4) Oil pressure should be approximately 200 kPa greater than the steam pressure

5) Fuel valve is opened before the steam atomizing valve

Carbon that is not combined with hydrogen is referred to as:

1) Fixed carbon

2) Mono-carbon

3) Loose carbon

4) United carbon

5) Separated carbon

Relative to boiler combustion, an exhauster fan:

1) Extracts solid particles from the flue gases

2) Exhausts dust from the coal crushers

3) Extracts ashes from a hopper

4) Extracts pulverized coal from a pulverizer

5) Is the same as an ID fan

The refining process for fuel oils involves separating the crude oil into end products which have distinguishing characteristics such as specific gravity, viscosity, and:

1) Heating value

2) Boiling point

3) Odor

4) Color

5) Solids content

A mechanical atomizing burner has oil pumped under high pressure through a:

1) Re-circulation line

2) Ring burner

3) Sprayer plate

4) Rotary cup

5) Multi-spud burner

The combustion equation 2H2+ O2=:

1) 2H + O₂

2) 2H₂O

3) 2H₂O + heat

4) H₂O + heat

5) H₂O

In winter, the white smoke coming from the stack is:

1) Carbon monoxide from incomplete combustion of the carbon in the fuel

2) Wet steam from combustion of the hydrogen in the fuel

3) Sulfur dioxide

4) Unburned hydrogen

5) Carbon dioxide

The balanced equation for the complete combustion of hydrogen is:

1) 2H₂ + O₂ = 2H₂O + heat

2) H₂ + O = H₂O + heat

3) H₂ + 2O₂ = 2H₂O + heat

4) 2H + O₂ = H₂O + heat

5) 2H₂ + 2O₂ = 2H₂O + heat

The main function of a gas burner is to:

1) Consume the combustion air

2) Regulate the amount of excess air

3) Regulate the gas flow into the furnace

4) Provide intimate mixing of the gas with combustion air

5) Shoot the gas into the furnace

The balanced equation for the incomplete combustion of carbon is:

1. C + O2 = CO2 + heat

2. 2C + O2 = CO + heat

3. C + 2O2 = 2CO + heat

4. 2C + 2O2 = 4CO + heat

5. 2C + O2 = 2CO + heat

A) 2C + O₂ = CO + heat

B) C + O₂ = CO₂ + heat

C) 2C + O₂ = 2CO + heat

D) C + 2O₂ = 2CO + heat

E) 2C - 2O₂ = 4CO = heat

If, during a flue gas analysis, the excess air to a boiler furnace is increased, the percentage of:

1) CO₂ should increase

2) CO should increase

3) CO₂ should decrease

4) O₂ should decrease

5) O₂should remain the same